The intestinal flora represents in the host organism a real ecosystem, establishing close connections with the digestive epithelia and the immune system which is associated therewith. The interactions between the various bacteria, just as between the bacteria and their host, are factors in the control of the equilibrium of the microbial flora and the development of certain acute or chronic pathological conditions. The digestive flora also participates in a certain number of functional activities and interferes with the digestion and absorption of certain nutrients. The significant role of the intestinal flora in human health was recognized at the beginning of the 20th century by the consideration that a certain number of diseases could be the consequence of a breaking of the equilibrium of the intestinal flora, and that the restoring of this equilibrium was beneficial in terms of health. However, the idea of incorporating microorganisms into the human diet or at least using the potential beneficial effects of the presence of these microorganisms appears to go back to very ancient times.
The intestinal ecosystem is established during the first months of life. Indeed, infants have no intestinal flora at birth. In utero, the intestine is sterile.
In newborn babies, the colonization of the digestive tract is relatively stereotyped during the first days, depending partly on the composition of the maternal vaginal and fecal flora; it is delayed in children born by cesarian. Bifidobacteria and Lactobacilli, and to a lesser extent Bacteroides and Clostridiae, appear as early as the third day. The implantation of this flora is directly dependent on the type of diet received, on the environmental conditions and on any prescription of antibiotics.
At the end of the first month, very clear differences exist in the composition of the intestinal flora according to the type of diet received by the newborn baby. Thus, the intestinal flora of breast-fed children is almost exclusively composed of Bifidobacteria. There are numerous bifidogenic factors in maternal milk and they could not be limited to only galactooligosaccharides.
On the other hand, the flora of babies fed with infant milks is rich in Enterobacteria and Gram-negative bacteria. As soon as the diet begins to be diversified, the difference between the flora of breast-fed children and that of artificially fed children becomes less marked, with an increase in the concentration of Escherichia coli, Enterococcaceae and Clostridiaceae. Between the age of one year and two years, the child acquires an intestinal flora that is virtually identical to that of the adult. This microflora remains relatively stable during the lifetime, except in the case of drastic changes in diet, of treatment with antibiotics, or of modulation through the ingestion of prebiotics or probiotics.
The term infant colic (IC) usually refers to a clinical entity characterized by the paroxysmal occurrence in an infant of less than three months of prolonged crying and of phases of agitation, the cause of which is presumed to be of intestinal origin. IC is often due to the fact that the infant, thus far fed directly via the umbilical cord and its bloodstream, has made very little usage of its digestive tract and even less of its stomach. In the first months, the adaptation of the digestive system, induced by digestion, produces digestive pain in the baby, called colic. The ingestion of air during feeding worsens the phenomenon since this produces gases. The term colic is used only if the infant is otherwise in good health and its weight is normal. It generally occurs at the end of the afternoon, after a meal. The child is agitated, folds its legs against its stomach, cries and is inconsolable until it finally emits a gas. IC does not necessarily have an effect on the stools of the infant, which generally remain normal.
The term enterocolitis, and more specifically the term necrotizing enterocolitis (NEC), denotes a pathological condition that is more serious, or even lethal in more severe cases. It is the result of various attacks which are often intricate. NEC is an inflammation of the small intestine or of the colon leading to frequent and not very consistent stools, which may be painful. It is an acquired pathological condition of newborn babies which is defined by the occurrence of multifocal necrosis of the intestinal wall characterized by the appearance of ischemic and hemorrhagic necrotic patches which can lead to ulcerations capable of progressing to digestive perforation. NEC usually occurs in premature newborn babies, between the 3rd and the 10th day of life; it is exceptional in full-term newborn babies. It results from a multifactorial attack of the mucosa. The physiopathology of NEC is multifactorial. Prematurity is the principal factor thereof. Finally, the digestive stasis, the enteral feeding and the immunological immaturity of newborn babies is thought to promote the occurrence of NEC. Dangerous and pathogenic microorganisms have been isolated in blood cultures and peritoneal fluid from newborn babies suffering from NEC: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis and also anaerobic bacteria responsible for severe forms with pneumatosis. There is constant degradation of the general condition, but the clinical picture is variable, ranging from the existence of isolated digestive signs (bloated and painful abdomen, bilious vomiting, arrest of transit) to that of septic signs (grayish complexion, hypothermia, apnea, state of oligoaneuric shock) in the severe forms.
Thus, in the first months of life, the colonization of the digestive tract is an essential step. Moreover, throughout life, a certain bacterial equilibrium must be ensured in order to maintain constant digestive well-being in the child and then in the adult.
The digestive tract is colonized by a very important microflora, implanted essentially in the colon, with great diversity since it is composed of more than 400 different species.
The role of a balanced intestinal flora is very important. The flora is involved in the degradation of polysaccharides, the fermentation of monosaccharides, the conversion of xenobiotics, the proteolysis of amino acids, the production of fermentative hydrogen and reuse thereof, the production of intestinal gases, the metabolism of bile acids, and the production of mutagens, but also and especially at the level of the development of the intestinal immune system (gut associated lymphoid tissue).
Thus, the equilibrium of the intestinal flora participates in regulating intestinal transit, in preventing the penetration of hostile antigens and in preventing the proliferation of pathogenic microorganisms. Many and often concomitant mechanisms are cited to account for the inhibition of pathogenic flora:                production of inhibiting substances such as organic acids, in particular of lactic acid, of hydrogen peroxide (H2O2),        occupation of adhesion sites on the intestinal mucosa or on the mucus coating it, thus thwarting the possibility for other microorganisms to attach thereto,        degradation of toxin receptor sites,        stimulation of immune functions, such as the production of immunoglobulins A (IgAs). IgAs are an antibody isotype predominantly produced at the level of the mucosae, where they constitute a first line of immune defense against toxins and infectious agents present in the environment. In the intestine, IgA production is strongly induced during the colonization of newborn babies by the intestinal flora, acquired during delivery and in the hours which follow,        competition with respect to nutrients.        
A growing interest has seen the light of day for the ecological control of the intestinal flora in human beings, and more particularly that of infants and of young children, through the administration of ingredients which can be categorized as three types:                Prebiotics are defined as a non-digestible substance which induces a physiological effect beneficial to the host by specifically stimulating the growth and/or the activity of a limited number of bacterial populations already established in the colon. This definition does not emphasize one bacterial population in particular. It is commonly accepted that a prebiotic increases the number of bifidobacteria and of lactic acid-producing bacteria, since these groups of bacteria are beneficial to the host. Thus, prebiotics are present in the intestinal lumen and stimulate the selective growth of a flora considered to be beneficial in terms of health. The key to their effectiveness is that they can be fermented by a specific intestinal microflora of which the development thus generated will be beneficial. This mode of action thus involves regular ingestion of the ingredient concerned. As a result, a certain number of studies have attempted to identify the potentially bifidogenic factors and certain oligosaccharides have ranked among the best of the candidates. Non-digestible oligosaccharides withstand hydrolysis by brush border enzymes and will behave like energy substrates for certain elements of the colonic flora, such as lactobacilli and bifidobacteria. The bifidogenic effect of prebiotics, and also their potential immunometabolic action, suggests that they may have a beneficial effect in particular in the context of the prevention of intestinal infections.        Probiotics are microorganisms which, once ingested, are capable of remaining alive during intestinal transit and of modifying the intestinal flora while having a demonstrated beneficial effect on the health; this is the major factor which determines the effectiveness thereof. The probiotics used are lactic acid-producing live micro-organic strains, such as lactobacilli, certain streptococci and bifidobacteria. Certain strains are, furthermore, capable of having an immunoregulatory role, in particular by stimulating IgA production and phagocytic capacity.        Symbiotics are defined as a product containing both one or more probiotic(s) and one or more prebiotic(s). The presence of prebiotic(s) exerts a beneficial effect on the stability of the probiotic(s) in the product and also on survival thereof and implantation thereof in the gastrointestinal tract, as long as the prebiotic is present.        
Among the numerous prebiotic candidates, the most well known and studied are fructans (FOSs: fructooligosaccharides, oligofructose and inulin) and other oligosides of galactose and transgalactose (GOSs and TOSs). The lactose, which escapes digestion in the small intestine, is also a prebiotic, and several studies have shown that lactose can reach the colon in infants. Numerous other carbohydrates could claim the name prebiotics (xylooligosaccharides, isomaltooligosaccharides, glucooligosaccharides, etc.). Some resistant starches and alcohol sugars could also have prebiotic properties. Lactulose is also a prebiotic.
The prebiotic ingredient must be perfectly characterized. The products or organisms responsible for the ingredient must be known and characterized, whether it is a question of an ingredient isolated from a vegetable, animal or microbial product, or of an ingredient produced by chemical or microbial synthesis.
The market for food products intended for infants and children under the age of three, who are in good health, has, for more than a century, always been, constantly driven by the companies which design and/or market these foods, in constant evolution. Today, European regulations, transcribed into national law, define in a more sophisticated manner the composition of the two types of milk formulae authorized for marketing, that is to say infant formulae (for children born at full term, from birth to 4 to 6 months), and follow-on formulae (for infants aged from 4-6 months to 12 months). The evolution of the compositions of these milk formulae has thus constituted considerable progress in terms of infant nutrition. The better adaptation to the nutritional needs and digestive capacities of young children of the protein, lipid and carbohydrate formula and of the mineral salt, trace element and vitamin contents has meant that, when the mother cannot or does not want to breastfeed, or when breastfeeding after the age of six months is no longer sufficient, these formulae make it possible to obtain normal somatic growth, and satisfactory psychomotor development, without any major pathological risk.
Armed with this finding and after numerous research studies, it is to the applicant companies' credit to have overcome all the demands required in infant nutrition by proposing a novel composition for feeding infants and/or young children. More specifically, the present invention relates to the field of prebiotics in infant nutrition.